Asset Retirement Obligations (Rollforward)(Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Asset Retirement Obligation [Roll Forward]
Balance as of January 1	$ 4,958us-gaap_AssetRetirementObligation	$ 5,176us-gaap_AssetRetirementObligation
Acquisitions	4	4
Accretion expense	246	239
Liabilities settled	(68)	(12)
Liabilities incurred in the current year	3,500
Revisions in estimates of cash flows	(174)	(449)
Balance as of December 31	8,466us-gaap_AssetRetirementObligation	4,958us-gaap_AssetRetirementObligation
Duke Energy Carolinas [Member]
Asset Retirement Obligation [Roll Forward]
Balance as of January 1	1,594	1,959
Accretion expense	113	122
Liabilities incurred in the current year	1,717
Revisions in estimates of cash flows	4	(487)
Balance as of December 31	3,428	1,594
Progress Energy [Member]
Asset Retirement Obligation [Roll Forward]
Balance as of January 1	2,570	2,420
Accretion expense	135	113
Liabilities settled	(68)	(12)
Liabilities incurred in the current year	1,783
Revisions in estimates of cash flows	291	49
Balance as of December 31	4,711	2,570
Duke Energy Progress [Member]
Asset Retirement Obligation [Roll Forward]
Balance as of January 1	1,737	1,656
Accretion expense	97	80
Liabilities incurred in the current year	1,783
Revisions in estimates of cash flows	288	1
Balance as of December 31	3,905	1,737
Asset retirement obligation, current		8	7
Duke Energy Florida [Member]
Asset Retirement Obligation [Roll Forward]
Balance as of January 1	833	764
Accretion expense	38	33
Liabilities settled	(68)	(12)
Revisions in estimates of cash flows	3	48
Balance as of December 31	806	833
Duke Energy Ohio [Member]
Asset Retirement Obligation [Roll Forward]
Balance as of January 1	28	28
Accretion expense	2	2
Revisions in estimates of cash flows	(3)	(2)
Balance as of December 31	27	28
Duke Energy Indiana [Member]
Asset Retirement Obligation [Roll Forward]
Balance as of January 1	30	37
Accretion expense	2
Revisions in estimates of cash flows		(7)
Balance as of December 31	$ 32	$ 30

Asset retirement obligations acquired from the acquisition of a business.

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- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Asset Retirement Obligation

-URI http://asc.fasb.org/extlink&oid=6505190

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- Definition

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

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- Definition

Current portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

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- Definition

Amount of asset retirement obligations incurred during the period.

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Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset.

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- Definition

Amount of the Increase or Decrease in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

+ References

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